Pharmaceutical Metal Expansion Bellows Now Available

Pharmaceutical Metal Expansion Bellows Now Available

Posted on November 8th, 2018 By Tim Robinson

Pharmaceutical Metal Expansion Bellows

Metal Bellows

FlexEJ has completed the design and fabrication of a batch of metal expansion joints for a UK pharmaceuticals manufacturer.

Specifying an expansion joint in a pharmaceutical production line can be problematic. For this project, the piping design required expansion joints but a fundamental requirement was ease of cleaning and a complete avoidance of product retention.

A possible solution could have been a pharmaceutical rubber expansion joint which is crevice free but its inherent design limits its flexibility and - as with any rubber expansion joint - it has a relatively low operating temperature limit.

This formed the basis of the specification brought to FlexEJ’s engineering team. The design case was to meet 270 DegC and 10 Bar G with a high degree of flexibility so a metal bellow would be best suited to this application. But in a conventional bellow or expansion joint the convolutions are prone to retain product or contaminants. A liner can sometimes be used but again product can get behind the liner so the problem is not entirely eliminated.

So how to maintain the highest standards of cleanliness inside the bellow once installed and in operation? The solution lay in designing a specific ‘open’ convolution profile which prevents contaminants getting lodged within the joint. The team’s clever design of profile, combining with the unit being used in vertical alignment leads to the bellow being self-draining – and at all movement positions. To achieve the high levels of purity and cleanliness required for this application’s flowing media, the bellow had to be fabricated in 316 stainless steel with a very high surface finish.

The expansion joint also includes threaded mounting bars – these enable the bellows to be contracted slightly to enable easy removal from the pharmaceutical line when required. The smooth, polished rods seen in the image here are limit bars to prevent accidental over-extension. Each joint is also fitted with pharmaceutical grade aseptic flanges – smooth on the inside and sealed with an ‘o’ ring. On completion, the complete units were electro-polished for additional surface improvement and cleaning – and that gives them their photogenic qualities seen here.

Please see our new pharmaceutical & aseptic metal bellows page more information about the options avaliable or call Gareth Hardy or our anyone in our technical sales team on +44 (0) 1384 881188 or drop us an email

Tim RobinsonTim Robinson is a FlexEJ director and can be contacted on +44 (0) 1384 881154 or via email at

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    FLEXEJ Ltd was formed in 2002 by two professional engineers who brought together an already highly respected design capability with business and commercial skills gained in large multinational companies.
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